Improved performance of microbial fuel cell through addition of rhamnolipid

An investigation aimed at exploring a new approach to improve microbial fuel cell (MFC) performance and electron transfer rate through the addition of rhamnolipid was carried out. Results demonstrated that, for an air-cathode MFC operating on 1 g L−1 glucose with different additions of rhamnolipid from 0 to 80 mg L−1, the open circuit voltage (OCV) was 1.8-fold increased from 483 to 878 mV, the maximum power density was 12.5-fold increased from 22 to 275 W m−3 (0.6 to 7.6 W m−2), while the corresponding current density of the maximum power density was 11.4-fold increased from 1.8 to 20.6 A m−2, respectively. Anode discharge analysis suggested that the improvement of electron transfer from bacteria to anode can be attributed to the addition of rhamnolipid. The high power density achieved here may be due to the increase of permeability of cell membranes by the addition of rhamnolipid, which reduced the electron transfer resistance through the cell membrane and promoted the electron transfer rate and number, consequently enhancing the current and power output. A promising way of utilizing bio-surfactant to improve the energy generation of MFC was demonstrated.